How do I export a simple Blender 3D model, without armature, to Three js?
I'm using Blender 2.73 and three.js (r70)

The io_three folder has to be copied to blender's scripts/addon folder for the "Import-Export: Three.js Format" to appear. But this has probably been figured out by you. 

During the export to three.js (.json) format you may want to include a few essential and additional attributes like vertices,faces,colors and materials for your model. By default, the following will be checked. 



Depending on the complexity of the image, you may get texture files in addition to the .json files. Use them. 

Now you have to basically re-create the model using a scene, camera, renderer and animation loop.

A tutorial with three.js basics --> http://www.kadrmasconcepts.com/blog/2011/06/08/three-js-blender-part-2/